1. Field of the Invention
The present invention relates to a system and method of injection blow molding and injection molding device, and particularly to a system and method of injection blow molding in which preforms are injection molded before temperature regulating, and then blow molded into containers.
2. Description of the Prior Art
One of the injection blow molding systems for molding containers is described in Japanese Patent Publication No. 3-45692, for example.
The injection blow molding system described in this Japanese Patent Publication No. 3-45692 is shown in FIG. 15 of the accompany drawings and comprises an injection molding station 2, a first temperature regulating station 4, a second temperature regulating station 6, a blow molding station 8 and a removing station 10, all of which are arranged in a line.
The injection molding station 2 simultaneously injection molds two rows of four preforms 12 arranged in a direction perpendicular to a preform carrying direction shown by an arrow in this figure. The pitch P1 between two rows of the injection molded preforms 12 (which will be referred to xe2x80x9cthe injection molding pitch P1xe2x80x9d) is then changed to a larger pitch P2 for blow molding in the blow molding station 8(which will be referred to xe2x80x9cthe blow molding pitch P2xe2x80x9d). The preforms 12 are then carried through the first and second temperature regulating stations 4, 6, blow molding station 8 and removing station 10 while the blow molding pitch P2 is maintained.
In the injection molding station 2, the preforms 12 are injection molded and carried in their upright state.
Since the injection blow molding system of Japanese Patent Publication No. 3-45692 is designed to change the injection molding pitch P1 to the blow molding pitch P2 immediately after the preforms 12 have been injection molded, the preforms 12 will be carried with this larger pitch P2 from the injection molding station 2 through the first and second temperature regulating stations 4, 6 to the blow molding station 8. This causes a waste of space in the first and second temperature regulating stations 4, 6, resulting in increase of the entire system size and manufacturing cost.
When beverage containers or the like are to be molded by such a system, it is desired to maintain the molding room clean. When such a clean atmosphere is to be maintained in the larger area, the installation and maintenance costs will be increased. To avoid this, it is important to reduce the area of installation as small as possible.
Furthermore, such an injection blow molding system is designed to carry the upright preforms 12. When the preforms 12 are heated, the necks of the erected preforms 12 may be excessively heated to be undesirably deformed because the necks of the preforms 12 are topped and the heat moves upward. In this case, further, carrying members used to carry the preforms may also be adversely affected by the heat.
Since the preforms 12 are blow molded by the blow molding station 8 in their upright state, the necessary parts for blow molding the preforms 12 such as stretching rods and others must be placed above the preforms 12. This will increase the entire height of the system and raise a problem in the installation space and maintenance.
An object of the present invention is to prevent any wasteful use of space when carrying the preforms and to improve the efficiency on molding.
Another object of the present invention is to reduce the installation area of the system to as small as possible.
Still another object of the present invention is to prevent the necks of the preforms from being excessively heated and also to avoid the preform carrying members from being adversely affected by the heat.
A further object of the present invention is to reduce the entire height of the system and also the installation space and also to facilitate the maintenance.
According to one aspect of the present invention, an injection blow molding system comprises:
an injection molding station for injection molding preforms;
a cooling station for cooling the preforms while carrying the preforms in a first direction;
a first delivering section for receiving the preforms from the injection molding station and delivering the preforms to the cooling station;
a heating station for heating the preforms cooled by the cooling station while carrying the preforms in the first direction;
a plurality of blow molding stations for stretch blow molding the preforms into containers; and
a second delivering section for receiving the preforms from the heating station and delivering the preforms to the blow molding stations;
wherein:
the injection molding station has an injection mold for simultaneously injection molding the preforms in an upright state, when the preforms are arranged in an Mxc3x97N (Mxe2x89xa72, Nxe2x89xa72) matrix having M rows extending parallel to a second direction which is perpendicular to the first direction and N columns in each row;
the first delivering section has a removing mechanism for removing the Mxc3x97N matrix of the preforms in an upright state out of the injection molding station, and an inverting mechanism for inverting the preforms to deliver to the cooling station;
the cooling station and the heating station have a first carrying path in common for intermittently carrying one row of N preforms at a time in an inverted state;
the second delivering section has a transfer mechanism for receiving the one row of N preforms heated by the heating station from the first carrying path to transfer to the blow molding stations in an inverted state; and
each of the blow molding stations includes:
a second carrying path having a substantially rectangular shape with two shorter sides and two longer sides;
a receiving section located on one of the shorter sides in the second carrying path for receiving the preforms from the second delivering section in a state of inversion;
a blow molding section located on one of the longer sides in the second carrying path for simultaneously stretch blow molding the preforms received by the receiving section into containers; and
a removing section located on the other shorter side opposite to the receiving section for removing the containers molded by the blow molding section.
According to the present invention, the system will not be spread in a direction perpendicular to the first direction because the injection molding station, first delivering section, cooling station, heating station, second delivering section and blow molding station are arranged linearly in the first direction. This can minimize the installation area and save the space. Particularly, the area of the clean room in which the beverage containers are molded can be more effectively used.
Since the injection molding station simultaneously injection molds Mxc3x97N preforms, the number of preforms for blow molding time can be secured to improve the efficiency in the molding cycle.
At the first delivering section, M rows of preforms are preferably delivered to the cooling station after the row pitch between M rows has been changed. By additionally cooling the preforms at the cooling station, the temperature in the injection molded preforms can be uniformly lowered so that the influence of the temperature control at the re-heating step will be increased to improve the stability on molding.
By heating the preforms cooled by the cooling station at the heating station in their inverted state, the necks of the preforms as well as the carrying members supporting the preforms in their inverted state will not be excessively heated. This can reliably prevent any deformation of the preform necks and the adverse effects of heat to the carrying members. In the cooling and heating stations, it is preferred that the preforms are rotated about their longitudinal axes by a rotation mechanism to cool and heat the preforms uniformly around their circumferences.
The inverted preforms are delivered from the second receiving section to the blow molding stations arranged parallel to one another. In each of the blow molding stations, the preforms are received by the receiving section located on the one shorter side of the second carrying path. The received preforms are simultaneously stretch blow molded by the blow molding section located on the longer side of the second carrying path. The molded containers are then removed by the removing section located on the other shorter side of the second carrying path. By blow molding the preforms in their inverted state, any elevator devices such as stretching rods and others are not required above the preforms. This can reduce the entire height and space required by the system and facilitate the maintenance. Since the blow molding section are located on the one longer side of the second carrying path, a blow clamping mechanism may be placed within the space between the longer sides of the second carrying path. This means that such a space can be more effectively utilized.
According to another aspect of the present invention, an injection blow molding station comprises:
an injection molding station for injection molding preforms in an upright state;
a carrying path for carrying the preforms in a first direction;
a delivering section for receiving the preforms from the injection molding station and delivering the preforms to the carrying path;
a heating station located on the carrying path for heating the preforms while carrying them a temperature equal to or higher than a proper stretching temperature; and
at least one blow molding station for stretch blow molding the preforms heated by the heating station into containers;
wherein:
the injection molding station includes:
an injection mold having upper and lower mold portions for simultaneously injection molding the preforms in an inverted state, when the preforms are arranged in an Mxc3x97N matrix (Mxe2x89xa72, Nxe2x89xa72) having M rows extending parallel to a second direction which is perpendicular to the first direction and N columns in each row;
an upper mold clamping plate on which the upper mold portion is mounted;
a lower mold clamping plate on which the lower mold portion is mounted; and
a clamping plate driving mechanism for moving the upper mold clamping plate in a vertical direction;
the carrying path includes carrying members arranged in parallel to carry one row of N preforms at a time; and
the delivering section includes:
M rows of removing plates each of which moves between the upper and lower mold portions in the injection molding station to receive N preforms; and
a removing mechanism which makes the M rows of removing plates advance toward and retreat from the injection molding station to remove the Mxc3x97N preforms, and which has a pitch changing mechanism for increasing a row pitch in the M rows of removing plates when advancing and for decreasing the row pitch when retreating.
According to this aspect of the present invention, the first delivering section delivers a plurality of injection molded preform rows to the heating station while reducing the row pitch between the injection molded preform rows in the preform carrying direction. Thus, time required to deliver the preforms can be reduced. The space required to carry and heat the preforms in the heating station can be reduced. This means that more preforms can be carried and heated within the same space and that the efficiency on molding can be improved. Furthermore, the entire length of the heating station can be reduced to save the space more. In addition, each of the removing and inverting mechanisms may be of a separate structure that can be reduced in weight and improved in operational speed.
In the above arrangement, it is preferred that the inverting mechanism may change the column pitch in the preforms while being inverted.
Each of the M rows of removing plates may have N cylindrical receiving members, each of which receives N preforms at a time with the portion thereof to be held by the holding members being exposed. In such a case, four holding members must be provided at four different heights. If the heights of these four holding members are also changed during the inverting step, time required to change these heights may be included in the inverting time. This means that the molding cycle can be reduced.
According to a further aspect of the present invention, an injection blow molding system comprises:
an injection molding station for injection molding preforms in an upright state;
a first carrying path for carrying the preforms in a first direction;
a first delivering section which includes a removing mechanism for removing the preforms from the injection molding station and a delivering mechanism for delivering the removed preforms to the first carrying path;
a heating station located on the first carrying path for heating the preforms while carrying to a temperature equal to or higher than a proper stretching temperature; and
at least one blow molding station for stretch blow molding the preforms heated by the heating station into containers;
wherein:
the injection molding station includes:
an injection mold having upper and lower mold portions for simultaneously injection molding the preforms in an upright state, when the preforms are arranged in a Mxc3x97N matrix (Mxe2x89xa72, Nxe2x89xa72) having M rows extending parallel to a second direction which is perpendicular to the first direction and N columns in each row;
an upper mold clamping plate on which the upper mold portion is mounted;
a lower mold clamping plate on which the lower mold portion is mounted; and
a clamping plate driving mechanism which has four tie-bars to move the upper mold clamping plate in a vertical direction;
the first carrying path includes carrying members arranged in parallel to carry the one row of N preforms at a time in an upright state; and
the removing mechanism of the first delivering section includes:
at least one removing plate which advances toward and retreat from the injection molding station to receive the preforms; and
a plurality of removing rails which conducts the at least one removing plate at its opposite ends into between the upper and lower mold clamping plates;
the removing rails are fixedly mounted between the lower mold portion and the four tie-bars, and extends from the injection molding station toward the first delivering section.
In the arrangement just mentioned above, the removing rails are fixedly mounted between the lower mold portion and the four tie-bars. Thus, the removing plates can be stably advanced or retreated by advancing/retreating members which can be reduced in weight. In addition, their associated components can be omitted.
It is further preferred that the first carrying path has separate rotation mechanisms for rotating the preforms about their longitudinal axes in the cooling and heating stations and that a non-rotation area is provided between the rotation mechanism wherein at least one row of preforms are stopped. Thus, the non-rotation area may include a gate cutting mechanism for cutting the gates of the preforms. Such a gate cutting mechanism can cut the gates of the cooled preforms before they are re-heated. This is because preforms can be more easily and reliably cut at their gates if they are not rotated and also heated.
The present invention further provides an injection blow molding method comprising:
an injection molding step for injection molding preforms in an upright state in an injection molding station;
a removing step for removing the preforms from the injection molding station in a first direction;
a first delivering step for inverting the removed preforms to deliver in an upright state;
a cooling step for cooling the delivered preforms while carrying in the first direction in an upright state;
a heating step for heating the cooled preforms while carrying in the first direction in an upright state;
a second delivering step for delivering the heated preforms in an upright state; and
a blow molding step for stretch blow molding the delivered preforms into containers;
wherein:
in the injection molding step, the preforms are simultaneously injection-molded when the preforms are arranged in a Mxc3x97N (Mxe2x89xa72, Nxe2x89xa72) matrix having M rows extending parallel to a second direction which is perpendicular to the first direction and N columns in each row;
in the removing step, a row pitch in the M rows is changed while the preforms are being removed;
in the first delivering step, a column pitch of the N columns is changed while the preforms are being inverted; and
in the cooling and heating steps, the one row of N preforms are carried at a time in the first direction.
According to the method of the present invention, the carrying space can be reduced by delivering the preforms to the cooling step while decreasing the row pitch in the preforms injection molded at the injection molding step. Since the preforms are inverted while changing the column pitch in the delivering step and also M rows of preforms are simultaneously delivered to the cooling step, time required to deliver the preforms can be reduced to shorten the molding cycle.
The preforms may be grouped into N/2 which are heated by two heating stations. The N/2 preforms heated by the respective heating station may be blow molded by each of two blow molding stations. Thus, the preforms simultaneously heated by each of the heating stations can be simultaneously blow molded by the respective one of the blow molding stations. This can equalize the quality of product in the blow molding step. Even if the number of preforms in one row increases, this can be treated without increasing the blow molding station in size.
The present invention further provides an injection molding device comprising:
an injection mold which includes upper and lower mold portion for simultaneously injection molding Mxc3x97N preforms (Mxe2x89xa72, Nxe2x89xa72) in an upright state;
an upper mold clamping plate for supporting the upper mold portion;
a lower mold clamping plate for supporting the lower mold portion;
a clamping plate driving mechanism which has four tie-bars to movie the upper mold clamping plate in a vertical direction; and
a removing mechanism for removing the Mxc3x97N preforms;
wherein:
the lower mold portion has an injection cavity mold;
the upper mold portion has an injection core mold and split neck cavity molds; and
the removing mechanism includes:
at least one removing plate which moves between the upper and lower mold clamping plates when opening of the injection mold and holds and removes the injection-molded preforms; and
a plurality of removing rails for conducting the at least one removing plate at its opposite ends.
In the injection molding device of the present invention, the clamping plate driving mechanism for only moving the upper mold portions can remove the Mxc3x97N simultaneously injection molded preforms by horizontally moving the at least one removing plate.
The removing rails may be mounted on a removing rail supporting plate which is fixedly mounted on the lower mold clamping plate. Thus, the removing plate can be more stably moved.
The present invention further provides a mold device for injection molding cylindrical bottom-closed preforms each having a neck, comprising:
a stationary mold clamping plate;
a movable mold clamping plate;
an injection cavity mold mounted on the stationary mold clamping plate;
an injection core mold which is clamped with the injection cavity mold when the movable mold clamping plate is driven;
an injection core mold fixing plate mounted on the movable mold clamping plate for fixing the injection core mold;
an injection core mold holding plate mounted on the movable mold clamping plate between the injection core mold fixing plate and the lower mold clamping plate;
split neck cavity molds which are clamped with the injection core mold;
a neck mold fixing plate including the split plates each of which holds the respective one of the split neck cavity molds;
a stripper plate disposed between the neck mold fixing plate and the injection core mold fixing plate to move relative to the injection core mold fixing plate, and
neck mold fixing plate guide rails for holding the neck mold fixing plate, the neck mold fixing plate being slidably movable relative to the stripper plate to guide the neck mold fixing plate in the direction in which the split neck cavity molds are opened;
wherein the stripper plate includes:
a connecting portion to a moving rod for moving the stripper plate; and
an engaging portion being engaged with a release rod which moves the stripper plate downward to release the preforms from the injection core mold; and
each of the injection core mold holding plate and injection core mold fixing plates has a bore through which the release rod extends.
In such a mold device, the preforms held by the injection core mold and split neck cavity molds can be released from the injection cavity mold by moving the movable mold clamping plate. Thereafter, the release rod is moved to move the stripper plate relative to the injection core mold fixing plate so that a gap will be created between the preforms and the injection core mold. At this time, the neck mold fixing plate guide rails may be slidably moved relative to the stripper plate to move the neck mold fixing plate. Thus, the split neck cavity molds are opened to release the preforms from the injection core mold and split neck cavity molds completely.